A vertical wind tunnel (VWT) is a wind tunnel which moves air up in a vertical column. Although vertical wind tunnels have been built for aerodynamic research, the most high profile are those used as recreational wind tunnels, frequently advertised as “indoor skydiving” or bodyflight, which have also become a popular training tool for skydivers. A recreational wind tunnel enables human beings to experience the sensation of flight without planes or parachutes, through the force of wind being generated vertically. Air moves upwards at approximately 195 km/h (120 mph or 55 m/s), the terminal velocity of a falling human body belly-downwards (lower speeds can be used for beginners; higher speeds for experts). A vertical wind tunnel is frequently called ‘indoor skydiving’ due to the popularity of vertical wind tunnels among skydivers, who report that the sensation is extremely similar to skydiving. The human body ‘floats’ in midair in a vertical wind tunnel, replicating the physics of ‘body flight’ or ‘bodyflight’ experienced during freefall.
Outdoor vertical wind tunnels can either be portable or stationary. Portable vertical wind tunnels are often used in movies and demonstrations, and are often rented for large events such as conventions & state fairs. Portable units offer a dramatic effect for the flying person and the spectators, because there are no walls around the flight area. These vertical wind tunnels allow people to fly with a full or partial outdoor/sky view. Outdoor vertical wind tunnels may also have walls or netting around the wind column, to keep beginner tunnel flyers from falling out of the tunnel.
Stationary indoor vertical wind tunnels include recirculating and non-recirculating types. Non-recirculating vertical wind tunnels usually suck air through inlets near the bottom of the building, through the bodyflight area, and exhaust through the top of the building. Recirculating wind tunnels, form an aerodynamic loop with turning vanes, similar to a scientific wind tunnel, but using a vertical loop with a bodyflight chamber within a vertical part of the loop. Recirculating wind tunnels are usually built in climates that are too cold for non-recirculating wind tunnels. The airflow of an indoor vertical wind tunnel is usually smoother and more controlled than that of an outdoor unit. Indoor tunnels are more temperature-controllable, so they are operated year-round even in cold climates.
Various propellers and fan types can be used as the mechanism to move air through a vertical wind tunnel. Motors can either be diesel-powered or electric-powered, and typically provide a vertical column of air between 6 and 16 feet wide. A control unit allows for air speed adjustment by a controller in constant view of the flyers. Wind speed can be adjusted at many vertical wind tunnels, usually between 130 and 300 km/h (80 and 185 mph, or 35 and 80 m/s), to accommodate the abilities of an individual and to compensate for variable body drag during advanced acrobatics.
There is an extensive patent literature in this area, with U.S. Pat. No. 4,457,509, dating from 1981, describes a ‘Levitationarium’ which has many of the features of a contemporary recirculating vertical wind tunnels. JP 2013-121536 A discloses a skydiving simulator in which an upward flow of air is formed in a flying chamber 516 in a recirculating ring-shaped wind tunnel. It is shown in FIG. 6: a skydiving simulator 500 is a recirculating wind tunnel 510 with two large loops, each loop forcing air up through the flying chamber 516 and recirculating it using a pair of large axial fans that force the air back around a large loop and up through the flying chamber 516. The recirculating wind tunnel 510 includes a first vertical duct 512 that feeds air upwards through the flying chamber 516; a pair of second vertical ducts 513, 513 disposed in parallel to the first vertical duct 512 and that bring the air downwards; left and right side horizontal ducts 514 at the top of the wind tunnel connect the first vertical duct 512 to the left and right side vertical ducts 513; left and right side horizontal ducts 515 form the lower loop of the wind tunnel.
In the first horizontal duct 514 located at the top of the recirculating wind tunnel 510, axial fan air blowers 520, 520 are disposed to send air AR to the second vertical ducts 513, 513, respectively. A recirculating air pathway 511 is formed.
The flying chamber 516, within which a flyer M flies, is situated in a section of the first vertical duct 512. In the flying chamber 516, the air AR from the blowers 520, 520 is adapted to move from below a floor surface 516a (typically a metal grid) to a ceiling 516b. One or more skilled flyers M can float upon and perform acrobatics on the high-speed moving air AR.
A doorway 516c, through which the flyer M enters and exits the flying chamber 516, is included in the side of the first vertical duct 512. But the doorway 516c can influence the flow of the air AR that is moving from the floor surface 516a side to the ceiling 516b side in the flying chamber 516, for example introducing turbulence, which can make the flyer flying within the flying chamber 516 feel uncomfortable about the airflow that is felt on his body. Reference may also be made to US2006/025227; this shows (item 1196) a small, flat air deflector bar on the entrance to the flight chamber, on the side facing the waiting chamber. There are other designs of air deflectors or impact protection placed around the entrance to the flight chamber, but these have little effect on reducing turbulence inside the waiting chamber.
It is very desirable to reduce or minimize the uncomfortable feelings due to air turbulence inside the waiting chamber, especially as vertical wind tunnels need to attract ordinary customers who are looking for an enjoyable recreational experience.